Rotary speed responsive switch



1956 J. K. GAYLORD ETAL 2,76l;034

ROTARY SPEED RESPONSIVE SWITCH Filed April 25, 1955 United States Patent ROTARY SPEED RESPONSIVE SWITCH James K. Gaylord and Lewis E. Thatcher, Chicago, Ill., assignors to Gaylord Products, Incorporated, Chicago, Ill., a corporation of Delaware Application April 25, 1955, Serial No. 503,424

Claims. (Cl. 20080) This invention relates to improvements in a device for actuating an electric switch in response to the rate of speed of a rotating body and refers particularly to an inexpensive, simple-acting device for energizing or deenergizing an electric circuit in response to the rate of speed of a rotating body regardless of the direction of rotation of said body.

In copending patent application Serial No. 505,478 filed May 2, 1955 in the name of Lewis E. Thatcher, a device is described for securing a predetermined degree of lateral or radial movement of a rotating member when the rate of rotation reaches a predetermined speed, the radial or lateral movement of the member being utilizable to initiate a predetermined control operation or produce a predetermined signal.

The present invention comprises a relatively simple device which employs the basic concepts set forth in said copending patent application and wherein the operation of the device is exceedingly simple and the device may be manufactured economically.

The features,-objects and advantages of the present invention will be apparent from the accompanying drawing and following detailed description.

In the drawing,

Fig. 1 is a longitudinal sectional view illustrating a device embodying the concepts of the present invention.

Fig. 2 is a transverse sectional view taken on line 2- 2 of Fig. 1, showing the electric switch in closed position.

Fig. 3 is a view similar to Fig. 2 showing the electric switch in open position.

Fig. 4 is a transverse sectional view similar to Figs. 2 and 3 illustrating a modification of the present invention.

Referring in detail to the drawing, 1 indicates a cupshaped housing having a bottom 2 and lateral wall 3. A closure disc 4 is adapted to be positioned upon the upper edge of the wall 3 and is secured thereto by cement 5 or the like thereby providing a closed compartment 6. A boss 7 is preferably formed integral with the bottom 2 and extends downwardly therefrom. A similar boss 8 is formed integral with the closure disc 4 and extends upwardly therefrom. A shaft 9 is journaled for rotation in the bosses 7 and 8, said shaft passing through the central portion of compartment 6.

The shaft 9 is adapted to be rotated by external means (not shown) which may be coupled to said shaft. If the device 1 is used in conjunction with an automotive vehicle, for instance, the shaft 9 may be coupled to the speedometer cable of the vehicle and consequently will rotate in timed relationship with said speedometer cable which, in turn, will rotate at a speed proportional to the movement of the vehicle. If a speedometer cable is coupled to the shaft 9 the cable sheath may carry a female coupling (not shown) which may be engageable with threads 10 formed upon the outer surfaces of the bosses and 8.

Although the present device is particularly adaptable 2,761,034 Patented Aug. 28, 1956 for use on automotive vehicles to control an anticreep device which may be carried by the vehicle or to control a speed governor, it is to be understood that the present invention is not to be specifically limited to this environment since it will find use in many other applications.

Within the compartment 6 an upper driving member 11 may be mounted upon shaft 9, the driving member 11 comprising a hub portion 12 and an outwardly extending flange portion 13. A lower driving member 14 may also be positioned within the compartment 6 and also be mounted upon shaft 9, said lower driving member comprising hub portion 15 and an outwardly extending flange portion 16. A key 17 may function to rigidly secure the driving members 11 and 14 to shaft 9 whereby said driving members are rotated when shaft 9 is rotated.

A driven member 13 loosely embraces the hub portions 12 and 15 of the driving members 11 and 14, said driven member being provided with a central aperture 19 which is sufficiently large to permit appreciable radial eccentric movement of the driven member with respect to shaft 9 and with respect to the driving members. The driven member 18 at its outer peripery is provided with a rim 29 which lies outwardly from the peripheries of the flange portions 13 and 16 of the driving members 11 and 14 respectively. The opposite faces of the driven member 18 and the opposed faces of the flanges 13 and 16 are spaced from each other and a plastic material 21 is positioned in said spaces, said plastic material being in contact with the inner surfaces of the flanges 13 and 16 and also in contact with the body portion of the driven member 18. The plastic material 21 comprises a material preferably having appreciable viscosity and shear strength whereby when the driving members are rotated the driven member tends to rotate through the frictional agency of the material 21. However, the driven member 18 is not positively coupled to the driving members and may move circumferentially with respect to the driving members or may move radially with respect to said driving members. Such movement, of course, is resisted by the viscosity and shear strength of the material 21.

The material 21 preferably comprises a silicone oil, grease or paste or may comprise a relatively heavy industrial grease. However, the silicone material is preferred because of its physical characteristics. For instance, its viscosity and shear strength remain substantially constant regardless of the rate of shear. in addition, the viscosity and shear strength of such silicones is substantially unaffected by temperatures throughout a relatively wide range. Consequently, the frictional resistance between the driving members and driven member remain substantially constant over a Wide range of operating conditions.

As has been described in the copending patent application hereinbefore identified, when a radial force is applied to the periphery of the driven member 13 and said force exceeds the force produced by the viscosity and shear resistance of the material 21, the driven member may be moved to an eccentric position with respect to the shaft 9 and with respect to the driving members 11 and 14. If the radial force is maintained upon the periphery of the driven member and the driving mem bers are rotated, a force is exerted by the eccentrically positioned driven member in opposition to the radial force. Under predetermined conditions of operation, depending upon a number of factors which will be hereinafter more fully described, the forces may be so balanced that the driven member will return to a concentric positended outwardly to form a switch compartment 22 in which a conventional electric snap switch 23 is positioned. The snap switch 23 comprises a frame plate 24 which carries a supporting flange '25, the frame plate 24 being mounted upon the inner face of wall 26. A resilient s vitch arm 27 is pivotally carried upon the flange and at its end carries a contact point 23 which is juxtaposed with respect to stationary contact point 29 carried upon the frame 24. Contact point 2.9 is connected to an electric conductor 39 which, at its opposite end may be connected to a suitable control circuit (not shown). 0nd conductor 31 connects with and grounds frame The conductor 31 also connects with the same circuit to which the conductor 30 is connected. When the switch arm 27 is positioned, as shown in Fig. 2, contact points 23 and 29 are closed and hence the circuit to which con ductors 3G and 31 is connected is energized. When the switch arm 27 is in the position shown in Fig. 3, the contact points 28. and 29 are separated and the external circuit is deenergized.

A pressure bar 32 is pivotally mounted upon the flange 25 and acts upon the lower end of the switch arm 27. The switch arm 27 is a resilient member and consequently exerts a resilient force upon the pressure arm 32 which tends to rotate said pressure arm in a counterclockwise direction, as viewed in Figs. 2 and 3.

An actuating lever 33 is pivotally mounted, as at 3 2 in Figs. 2 and 3, upon a portion of the bottom of the housing It. The actuating lever is crimped to form arcuate projections 35 and 36, said projections being spaced from each other. The lever 33 is of such length and is so positioned with respect to shaft 9 that when the driven member 13 is in concentric position with respect to said shaft, the periphery or rim 26 of the driven member contacts both projections 35 and 36. The arm 32 bears upon the lever 33 intermediate the length of the lever and tends to urge, by virtue of the impelling force of the spring switch arm 2?, the lever into contact with the rim 21": of the driven member 18. Thus, a radial force is normally exerted against the periphery 2t) of the driven member 18 which will tend to move said driven member to an eccentric position with respect to the shaft 9 when the strait 9 is stationary. This position of the parts is shown best in Fig. 3.

if the shaft 9 is rotated in a clockwise direction, the driven member tends to rotate with the driving members it and i and in view of the fact that the driven member is initially in an eccentric position with respect to the shaft 9, said driven member exerts a force upon the lever tending to rock said lever in a clockwise direction, as viewed in Fig. 3, about the pivot point The force exerted by the driven member is exerted essentially against the crimp 35. As can readily be seen the lever 33 will tend to hold the driven member in the eccentric position shown in Fig. 3. However, in view of the fact that the force opposing said lever is a function of the speed of rotation of the shaft 9 said force, if it is of sufficient magnitude will rock the lever 33 about the pivot and if the force is of sufficient magnitude it will rock said lever to the position shown in Fig. 2, that is, it will rock it a sufficient degree to actuate the switch 23 to closed position. If the magnitude of the force is less. the lever 33 will be rocked a predetermined degree but not a suflicient degree to actuate the switch 23.

When the speed of shaft 9 reaches a predetermined rate sutiic'ent to close the switch 23, the lever 33 will he rocked into contact with a stop 37 which is mounted P -rt bottom 2 of the housing 1.

i f the speed of shaft 9 is in excess of that essential to bring the driven member 18 to its concentric position with respect to the driving members the driven member would tend to eccentrically move about shaft 9 and said eccentric movement would persist. However, when the speed of shaft 9 reaches a predetermined rate sufiicient to rock lever 33 into contact with the stop 37, the driven member 23 will have been moved to a concentric position with respect to the driving members and thereafter if the speed of shaft 9 increases, the driven member 13 will not be permitted to move beyond the concentric position by virtue of the fact that the crimps 35 and 36 having once centralized the driven member 18 will maintain said driven member in its concentric position.

if shaft 9 begins to slow down after it has caused the driven member to move to concentric position, the force opposing the lever 33 is reduced since, as has been herei .forc described, the lever-opposing force is a function of the rate of rotation of the shaft 9. A point will be reached in the operation wherein the force of lever 33 will overbalance the force due to rotation and hence said lever will tend to move the driven member to eccentric position. As said speed decreases, the lever 33 will have moved the driven member 18 to a position such that switch arm snaps open and thus the external circuit deenergized.

in view of the fact that the operation of the device is dependent upon the balance of the radial force of the lever 33, and the force produced upon the driven incin her 18 through the agency of the material 21 coupled vith the rate of rotation of the shaft 9, a proper selection of the material 21 as to its characteristics of viscosity and shear strength can be made so as to cause the driven member 38 to move into concentric switch-actuating position at predetermined speed. By virtue of the stop 37' coupled with the operation of the crimps 35 and 36, the driven member, at all speeds above said critical speed. will remain in concentric position.

in addition to the physical characteristics of the material 21 in determining the critical speed at which the "tch 23 will. operate, the thickness of the layer of material Zl between the driving lianges 13 and i6 and the driven member also constitutes a factor. The thicker the layer of the material 21 is, the lesser its shear force will be. in addition, the area of contact of the material 21 with the respective faces of the driving and driven members is also a factor. Thus, the construction of the driving and driven members with respect to each other and with respect to their spacing coupled with the physical characteristics of the material 21 will determine the rate or speed at which the switch 21 is operated and by the proper correlation of these factors the switch can be made to operate at substantially any speed of rotation of shaft 9.

As has been hereinbefore described, the operation of the parts was explained when shaft 9 rotates in a clockwise direction as viewed in Figs. 2 and 3. if the shaft 9 rotates in a counterclockwise direction the operation will be substantially the same. However, in this instance the major portion of the resistance of the driven member 18 tending to oppose the force of the lever 33 will be borne by the crimp 36 rather than the crimp 35. Hence. by the provision of the spaced crimps 35 and 36 the device will be responsive to a predetermined s eed of operation regardless of the direction of rotation of the shaft 9.

Referring particularly to Fig. 4, a slight modification of the invention is shown. All parts of the device are similar to that hereinbefore described with the exception of the association of the switch 23 and the driven rotor. and without further description similar parts in Fig. 4 will be designated by the same reference numerals which designate corresponding parts hereinbefore described.

In the form of the invention illustrated in Fig. 4, switch :1 27 is directly connected with lever 38 which is pivoted upon flange 25 instead of being pivoted upon the bottom of the housing, as hereinbefore described. The lever carries crimps 39 and 46 similar to crimps 35 and 36, hereinbefore described.

The operation of the device shown in Fig. 4 is similar to the operation of the device shown in Figs. 1, 2 and 3 except for the pivoting of lever 38 and the elimination of the arm 32.

Other modifications of the invention which do not depart from the spirit of the invention will be suggested to those skilled in the art and, hence, it is not intended that the invention be limited to the precise details of construction shown except as necessitated by the appended claims.

We claim as our invention:

1. A device for controlling an electric circuit in rcsponse to the rotary speed of a rotating body which comprises, a pair of driving members disposed in spaced relationship to each other, a driven member loosely disposed between said driving members and eccentrically movable with respect thereto, a lever pivotally mounted adjacent the peripheries of said members, a pair of spaced projections carried by said lever for making contact with the periphery of the driven member, an electric snap switch having a spring impelled actuating arm disposed adjacent said lever, means connecting said actuating arm to said lever whereby said spring-impelled arm resiliently urges said lever into radial contact with said driven member to move said driven member to an eccentric position when said driving members are stationary whereby said switch is manipulated in a predetermined direction, means for frictionally connecting said driving members to said driven member whereby rotation of said driving members at a predetermined speed urges said driven member to a substantially concentric position to manipulate said switch in the opposite direction, and a rotating body upon which said driving members are mounted for rotating said driving members.

2. A device for controlling an electric circuit in re sponse to the rotary speed of a rotating body which comprises, a pair of circular driving members disposed in face-to-face spaced relationship to each other, a driven member loosely disposed between said driving members in face-to-face relationship therewith and eccentrically movable in plane-parallel relationship with respect thereto, a lever pivotally mounted adjacent the periphery of said driven members, a pair of spaced projections carried by said lever for making contact with the periphery of the driven member at circumferentially spaced points on its perphery, an electric snap switch having a spring impelled actuating arm disposed adjacent said lever, means connecting said actuating arm to said lever whereby said spring-impelled arm resiliently urges "at least one of said projections upon said lever into radial contact with said driven member to move said driven member to an eccentric position when said driving members are stationary whereby said switch is manipulated in a predetermined direction, means for frictionally connecting said driving members to said driven member whereby rotation of said driving member urges said driven member to a concentric position to move said lever and manipulate said switch in the opposite direction, and a rotating body upon which said driving members are mounted for rotating said driving members.

3. A device for controlling an electric circuit in response to the rotary speed of a rotating body which comprises, a pair of driving members disposed in spaced relationship to each other, a driven member loosely disposed between said driving members and eccentrically movable with respect thereto, a lever pivotally mounted adjacent the peripheries of said members, a pair of spaced projections carried by said lever for making contact with the 6 periphery of the driven member, a stop member to limit movement of said lever away from said driven member, an electric snap switch having a spring impelled actuating arm disposed adjacent said lever, means connecting said actuating arm to said lever whereby saidspring-impelled arm resiliently urges said lever into radial contact with said driven member to move said driven member to an eccentric position when said driving members are stationary whereby said switch is manipulated in a predetermined direction, means for frictionally connecting said driving members to said driven member whereby rotation of said driving members urges said driven member to a concentric position to move said lever into contact with said stop member and manipulate said switch in the opposite direction, and a rotating body upon which said driving members are mounted for rotating said driving members.

4. A device for controlling an electric circuit in response to the rotary speed of a rotating body which comprises, a pair of circular driving members disposed in face-to-face spaced relationship to each other, a driven member loosely disposed between said driving members in face-to-face relationship thereto and eccentrically movable with respect thereto, a lever pivotally mounted adjacent the peripheries of said members, a pair of spaced projections carried by said lever for making contact with. the periphery of the driven member, an electric snap switch having a spring impelled actuating arm disposed adjacent said lever, means connecting said actuating arm to said lever whereby said spring-impelled arm resiliently urges at least one of said projections upon said lever into radial contact with said driven member to move said driven member to an eccentric position when said driving members are stationary whereby said switch is manipulated in a predetermined direction, relatively viscous plastic means disposed between the opposed faces of said driving and driven members for frictionally connecting said driving members to said driven member whereby rotation of said driving members urges said driven member to a concentric position to manipulate said switch in the opposite direction, and a rotating body upon which said driving members are mounted for rotating said driving members.

5. A device for controlling an electric circuit in response to the rotary speed of a rotating body which cornprises, a rotatable shaft, a pair of similar driving members disposed in spaced relationship to each other upon said shaft, a circular driven member loosely embracing said shaft and disposed between said driving members and eccentrically movable with respect thereto, a lever pivotally mounted adjacent the peripheries of said members, a pair of spaced projections carried by said lever for making contact with the periphery of the driven member, an electric snap switch having a spring impelled actuating arm disposed adjacent said lever, means connecting said actuating arm to said lever whereby said spring-impelled arm resiliently urges said lever into radial contact with said driven member to move said driven member to an eccentric position when said driving members are stationary whereby said switch is manipulated in a predetermined direction, means for frictionally connecting said driving members to said driven member whereby rotation of said driving members urges said driven member to a concentric position to manipulate said switch in the opposite direction.

No references cited. 

